IIs there a way to have milkweed in a community garden but limit its spread?
Milkweed sends out rhyzomes some distance. I cut off the plants that are not in a good spot and they usually do not come up again in that spot. Rhyzome spreading plants like bamboo are contained by barriers under ground, but they need to go very deep to be effective. Metal or concrete is used. Alternatively, you can dig out the roots in spring when they are in undesireable places, but the root structure is quite expensive.
You can create a pit lined by bricks a few feet down, but do not be surprised if plants come up outside the pit in a few years. I think cutting off the undesireable plants is the most practical solution.